JP2001254318A - Structure fof fixing cable to anchorage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixing structure having excellent reliability and profitability, preventing the enlargement more than required of an anchorage by the rational arrangement of a PC steel material for anchorage in the structure for fixing a cable to the anchorage by a correspondence type prestress system. SOLUTION: Strands 1a constituting the main cable 1 are dispersed in the vertical and horizontal direction from the positions S of saddles for the anchorages A, and fixed to connecting jigs 3 dispersed and arranged at the front fixing positions F. Both ends of tendons 2 such as the PC strands arranged in concrete for the anchorages A in a U shape are fixed to each connecting jig 3, and the main cables 1 are fixed onto the anchorage A through the connecting jigs 3 by the tension of the tendons 2. The tendons disposed in the U shape to the same cables 1 and the tendons disposed in the U shape among the main cables 1 and other main cables 1 can be mixed and made to exist as the tendons 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing structure of a cable used for fixing a main cable such as a suspension bridge to an anchorage.

[0002]

2. Description of the Related Art An anchoring structure of a main cable of a suspension bridge is a tunnel anchor type anchoring structure in which a slope is excavated in rock and concrete is cast and anchored, and a gravity type concrete anchorage (or called an anchor block). ) For fixing.

[0003] The former is adopted when the rock is relatively good and the tensile force can be resisted by the rock. In the latter, the anchorage is fixed by the weight of the anchorage and the friction of the bottom surface and the resistance of the side surface. However, in any of the above, when directly fixing the main cable, the workability,
In addition to the cost problem, there is a problem that the main cable cannot be replaced.

Accordingly, it is generally more reasonable to fix the main cable by exchanging the tensile force of the main cable with another member than to extend and fix the main cable as it is.
Such fixing structures include the following. Tensile material system As shown in FIG. 5, the strands 1a of the main cable 1 are dispersed and fixed on an anchor frame 12 made of a shape steel called a tensile material, and are fixed to the anchorage A using the friction of the steel material side surface. It is. As shown in the drawing, there are a structure in which the front girder 11 is provided and the front is fixed, and a structure in which the front girder is used and the fixing is performed by supporting the rear surface.

Prestressing method (non-compliant type) A PC in which a girder 11 is provided on the front surface to disperse and fix the strands 1a of the main cable, and the front girder 11 is arranged from the back surface or the inner chamber of the anchorage A.
The tension member 14 such as a steel material is fixed by being tensioned. Once received by the front girder 11, the axis of the strand 1a does not coincide with the axis of the tendon 14, and the dimensions of the rear surface of the anchorage can be reduced by disposing the tendon 14 in parallel.

Prestressing method (corresponding type) A plurality of connecting jigs 16 are provided on the front surface, the strands 1a of the main cable are dispersed and fixed, and the connecting jigs 16 are arranged from the back of the anchorage A or the chamber inside. P
The tension member 14 such as C steel is tensioned to be fixed. Since the connecting jig 16 bears only the tensile force, the axis of the strand 1a and the axis of the tendon 14 are usually aligned.

[0007]

SUMMARY OF THE INVENTION The present invention solves the following problems in the compliant prestress method described in the section of the prior art.

Since the strands 1a are dispersed at an angle, if the tension members 14 are arranged in a straight line, the size of the rear surface on which the tension members 14 are fixed increases, and the overall size of the anchorage A becomes unnecessarily large. Costs may increase.

Usually, a space called a chamber for fixing the rear surface of the tension member 14 is required inside the anchorage A, and the structure of the anchorage A is complicated. In addition,
Although it is possible to bury the fixing tool, it is not preferable because the reliability of the construction is not guaranteed.

The fixing work of the tension member 14 is performed in a narrow space, and the workability is poor.

After the tension member 14 is tensioned, it is necessary to dehumidify the inside of the chamber, fill the rust preventive material, fill concrete, and the like as measures for preventing the fixing device 15 from rusting.

The fixing tool 15 is expensive.

[0013] It is necessary to continuously cast the concrete of anchorage A, but when fixing device A is installed together with the concrete casting of anchorage, it is necessary to extend the casting cycle to improve the quality of concrete. Not preferred.

In order to install the fixing device 15, usually,
Although a gantry is required, rigidity of the gantry is required to a certain degree or more in order to secure required accuracy in installing the fixing device 15, and the weight of the steel material increases. Also, the gantry does not require any structural function after casting, which is uneconomical.

[0015]

According to the first aspect of the present invention, there is provided a fixing device in which a strand constituting a cable is arranged in a cross-section of an anchorage via a plurality of connecting jigs arranged in a distributed manner in front of the anchorage. In the anchoring structure of the cable connected to the tension member to the anchorage, the tension member is arranged in a folded shape within the anchorage cross section, and both ends of the tension member are connected to the connection jig on the front surface of the anchorage. It is characterized by having.

As the tensioning material for fixing, PC steel wire, PC
There is no particular limitation as long as it can be tensioned with a high tension, such as a strand made of a PC steel material such as a PC steel rod, or other new materials such as aramid fiber, carbon fiber, or glass fiber. These tendons are usually installed through a sheath tube previously buried in the anchorage.

The connecting jig is for securely fixing and connecting the ends of the strands constituting the cable and the ends of the tension members for fixing, and is basically a conventional corresponding type press. It can be considered in the same manner as the connection jig used in the stress type fixing structure.

The number of strands and tension members attached to a single connecting jig is not particularly limited.
Regarding the fixing of a cable, various combinations of one to several strands of a large number of strands constituting the cable and a tendon can be used.

In a second aspect of the present invention, in the fixing structure according to the first aspect, the case where the folded portion of the tension member has a gentle curved shape is limited. As a general form, the tendon is arranged in a U-shape, particularly at the folded portion. As described above, the present invention relates to an improvement of a fixing structure of a compliant prestressing type in which a strand of a cable is connected to a tension member with a connecting jig distributed and arranged, and the cable and the tension member correspond to each other. The need for a fixing device provided on the rear surface of the anchorage or in the internal chamber is eliminated.

Further, conventionally, since the tendon is fixed to the rear fixing device, a frame which is usually used becomes unnecessary, and the amount of steel material and the amount of the sheath tube in the folded portion are increased. Since the accuracy is lower than that of the fixing device, it is economical as a whole. Further, since the rear-side fixing device is unnecessary, the rear-side fixing dimension can be reduced.

Also, regarding the folded portion of the tendon,
Since a compressive stress is generated in the inner concrete, cracks can be prevented at this portion. In particular, this effect is great when the U-shaped loose arrangement is used.

[0022]

FIG. 1 shows an embodiment of the fixing structure of the present invention. FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). Each of the two main cables 1 is a strand 1a extending vertically and horizontally from the saddle position S of the anchorage A.
Are dispersed and guided to the front fixing position F. At the front fixing position F, the strands 1a are fixed to the connecting jigs 3 arranged in a distributed manner.

Each connecting jig 3 is fixed at both ends of a tension member 2 such as a PC strand arranged in a U-shape in the concrete of the anchorage A, and the tension of the tension member 2 causes the main cable 1 to be fixed. It is fixed to the anchorage A via the connecting jig 3. Looking at the arrangement of the tension members 2,
At the connecting jig 3 position, the strand 1a of the main cable 1
Are dispersed so as to coincide with the axis of, and the tip is curved and narrowed, and is arranged in a U-shape with a radius of curvature that does not cause a problem in terms of stress.

FIG. 2 conceptually shows the U-shaped arrangement of the fixing tendons 2. In this example, two tendons 2 are connected to the same main cable 1 for two main cables 1. On the other hand, there is a mixture of U-shaped ones and a U-shaped one between the other main cable 1.

In the case of fixing two main cables 1 in the conventional rear-side fixing method, there is a problem of interference between the tendon materials spreading radially on the rear side of the fixing, but a U-shape is formed between the two main cables. By doing so, the problem of interference is eliminated, and the distance between the main cables 1 can be reduced.

From another viewpoint, when the strands 1a constituting the main cable 1 are divided into an appropriate number and fixed to the connecting jig 3, a U-shape cannot be formed between the strands 1a of the main cable 1 on one side. In this case, it is possible to form a U-shape with the strand 1a of the other main cable 1.

FIG. 3 shows an example of the binding and distribution of cable strands in the fixing structure of the present invention. FIG. 3A shows the positional relationship of the bundles in the bundled state at the saddle position, and FIG. 3B shows the positional relationship of the strands in the dispersed state at the front fixing position by the connecting jig. Although each is conceptually shown, the drawing merely shows the positional relationship between the strands, and the dimensional relationship or the scale is completely different from the actual one.

In this example, 154 strands constituting one main cable are divided into 37 sets and fixed to 37 connecting jigs. In principle, four strands are fixed as one set to one connecting jig. However, when dispersing the strands from the saddle position, if the four strands cannot be combined into one set, one strand is used for the connecting jig. (See Fig. 3 (b)).

The 37 connecting jigs are fixed at the front fixing position by a tension member such as a PC strand arranged in a U-shape in the concrete of the anchorage, and these tension members are arranged in the vertical or horizontal direction. Although a U-shaped set is used, a part of the U-shape is formed so as to be connected to another main cable.

FIG. 4 shows an example of a connecting jig 3 for connecting the end of the cable strand 1a and the end of the tension member 2 for fixing at the front fixing position. The upper end of the tension member 2 that penetrates the center of the connecting jig 3 from below is the fixing plate 3
b, is fixed to the upper part of the connecting jig 3 via the supporting plate 3c and the like, and the main cable strand 1a can be fixed to the four outer periphery of the connecting jig 3 via the supporting plate 3d, the shim plate 3e, the socket 3f and the like. It has become.

[0031]

According to the present invention, there is no need for a fixing device for fixing a tendon such as a PC steel material disposed in the anchorage, so that construction costs, material costs, and the like are reduced, which is economical.

Since there is no fixing portion for fixing the tension member in the anchorage or on the rear surface, a space for inspection (such as a chamber) is not required.

By arranging the tension members in a curved manner, a compressive stress is generated in the concrete of the anchorage, and the occurrence of cracks can be prevented.

The anchorage can be reduced in size by the U-shaped or other curved arrangement of the tendon members, and the construction cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a fixing structure according to the present invention, in which (a) is a vertical sectional view and (b) is a sectional view taken along line AA.

FIG. 2 is a perspective view conceptually showing a U-shaped arrangement of a tension member for fixing in the embodiment of FIG. 1;

FIGS. 3A and 3B show the binding and dispersion of cable strands. FIG. 3A is a conceptual diagram showing the positional relationship of the bundles in a bundled state at a saddle position, and FIG. It is a conceptual diagram which shows the positional relationship of each strand of a distributed state at a position.

FIG. 4 shows an example of a connecting jig for connecting an end of a cable strand to an end of a tension member for fixing at a front fixing position, where (a) is a longitudinal sectional view and (b) is a longitudinal sectional view thereof. FIG. 7B is a cross-sectional view taken along the line BB (different cross sections are shown on the left and right sides of the shaft core), and FIG.

FIG. 5 is a vertical sectional view showing an example of a conventional fixing structure using a tension member system.

FIG. 6 is a vertical cross-sectional view showing an example of a conventional fixing structure using a non-compliant prestressing method.

FIG. 7 is a vertical sectional view showing an example of a conventional fixing structure using a corresponding prestress method.

[Explanation of symbols]

A: Anchorage, S: Saddle position, F: Front fixing position, 1: Main cable, 1a: Strand, 2: Tensile material, 3: Connection jig, 3a: Grout cap, 3b: Fixing plate, 3c: Support plate 3d: support plate, 3e: shim plate, 3f: socket, 3g: support plate, 11: front girder, 12: anchor frame, 13: rear girder, 14
... tension material, 15 ... fixing tool, 16 ... connecting jig

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideki Okubo 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. F-term (reference) 2D059 AA43 BB06 CC23 DD27 DD28 2E164 BA06 BA12

Claims (2)

[Claims] 1. A fixing method of a cable, comprising connecting a strand constituting a cable to a tension member for fixing arranged in a cross section of the anchorage via a plurality of connecting jigs dispersedly arranged on the front surface of the anchorage. In the structure, the tension member is arranged in a shape folded back in the cross section of the anchorage, and both ends of the tension member are connected to the connecting jig on the front surface of the anchorage, and a fixing structure of the cable to the anchorage. . 2. The fixing structure of a cable to an anchorage according to claim 1, wherein the folded portion of the tension member has a gentle curved shape.